Nabalus is a small genus of
plants (ca. 18 spp.) found in North America and East Asia.
Three species are relatively common in Central New York: N. albus, N.
altissimus and N. trifoliolatus1. Populations
tend to be small and infrequent, found mostly in wooded habitats.
Of other genera in the flora of North America, Nabalus is
probably most closely related to Lactuca (wild lettuces).

Vernacular names for this genus
include rattlesnake root, lion's foot and white lettuce.

This genus had long been
known by the scientific name Prenanthes. However, recent
phylogenetic research has determined that our species do not belong in
the Eurasian genus Prenanthes. Kilian,
et al. (2009), Bogler
(2006), Haines (2011).

In general, Nabalus
species are perennials, typically producing a single, erect stem
from a taproot. The sap is milky white. Branching is usually
alternate. The overall
inflorescence varies from
extremely tall and narrow to quite wide and diffused. Branch
inflorescences consist of small, compact clusters of
flower heads distributed along lateral branches or in stem leaf axils.
Flower heads are borne on short
peduncles, nodding/drooping
(pendulous) when in flower, and small, each containing only from 4 to 14
florets. Involucral bracts of our 3 common species are
glabrous,
various shades of green or pinkish-green, and occur in two series, an inner series of
longer more/less equal-length bracts, and an outer series of much
smaller bracts.

Leaf size and shape are quite variable across different populations, within populations and even on the
same plant. Leaf shape may be ovate, triangular or
lanceolate; lobed,
divided or "simple" (i.e., neither lobed nor
divided). The general pattern is for lower stem leaves to be
larger, broader and more often lobed or divided than upper stem leaves.

Though
our species of Nabalus are few in number, they are nevertheless
rather difficult to distinguish, for they are morphologically similar
and share many character states. Leaves and stems are usually not
diagnostic. It is not possible to confidently identify immature
plants from leaves alone. The best way to identify these species
is from examination of flowers and fruits. Floret and involucral
bract counts (per flower head), color of the pappus bristles and
involucral bract surface characteristics are the
most useful distinguishing characters. For additional details
visit the species pages at: N.
albus, N.
altissimus, N.
trifoliolatus.

Table
1 (below) summarizes the logic for identification. N.
serpentarius is also included in the following table for comparison
in case new populations are found.

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1Only one
collection of N. serpentarius is on record for the region (in
Chemung Co., 1897). It
is not known if that population has persisted.